This invention relates to stereo imaging systems, devices, and methods. In particular, the invention relates to a method of imaging a target site with a stereo imaging system, a method of aligning images of a stereo imaging system, a method of adjusting the stereo working distance of a stereo imaging system, and a stereo imaging system.
In minimally invasive surgery such as laparoscopic surgery, for example, a patient's abdomen is insufflated with gas, and trocar sleeves or cannulas are passed through small incisions to provide entry ports for laparoscopic surgical instruments. The laparoscopic surgical instruments generally include an endoscope in the form of a laparoscope for viewing the surgical site or field and surgical instruments defining end effectors such as clamps, graspers, scissors, staplers, and needle holders. The surgical instruments are similar to those used in conventional (open) surgery, except that the working end of each tool is separated from its handle by an elongate shaft. To perform surgical procedures, the surgeon passes instruments through the trocar sleeves and manipulates them from outside the abdomen by sliding them in and out through the sleeves in the abdominal wall, and actuating end effectors on distal ends of the instruments, while viewing the surgical site through the laparoscope.
In robotically-assisted and telerobotic surgery (both open and endoscopic procedures), the position of the surgical instruments is typically controlled by servo motors rather than directly by hand. The servo motors follow the motions of a surgeon's hands as he or she manipulates input or master control devices whilst remotely viewing the operation via an image displayed on a viewer, the viewer being operatively linked to an image capture device typically in the form of an endoscope. The viewer and its associated image capture device form part of an imaging system. The servo motors are typically part of an electromechanical surgical apparatus, which typically includes robotic arms that support and control the surgical instruments that have been introduced into e.g. an open surgical site, or through trocar sleeves into a body cavity, such as the patient's abdomen, or the like. During the operation, the master control devices provide mechanical actuation and control of a variety of surgical instruments. Such surgical instruments can typically include tissue graspers, needle drivers, etc., that can perform various surgical procedures for the surgeon, i.e., holding or driving a needle, grasping a blood vessel, dissecting tissue, and the like, while the surgeon views the procedures on the viewer.
It will be appreciated that the imaging system should meet certain criteria to render it suitable for use in applications such as minimally invasive surgical applications. In particular, the image displayed to the surgeon should be clear and optically correct. Furthermore, the imaging system should provide an adequate field of view and adequate resolution and brightness, so as to enable the surgical field to be adequately visualized by the surgeon.
Stereo endoscopes are sometimes used to provide the surgeon with a stereo image at the viewer. Stereo endoscopes are typically arranged to have a fixed point of intersection between two viewing axes. The distance between the fixed point and an object viewing end of the endoscope is referred to as the “working distance” of the endoscope. In use, the surgeon, whilst performing a surgical procedure, may want to observe an object removed from the point of intersection. For example, when using the endoscope to “search” for the surgical site, the surgeon typically observes objects at a working distance beyond the point of intersection. When the surgical site is reached, he or she may want to observe objects which are closer to the viewing end of the endoscope or beyond the point of intersection when the surgical procedure is actually performed.
Additionally, stereo endoscopes are not always precisely optically aligned due to, e.g., manufacturing constraints, and the like. In other words, the viewing axes sometimes do not intersect either precisely or at all. When such an endoscope is used, without compensating for such misalignment of the viewing axes, it could lead to the surgeon experiencing premature eye strain, headache, and/or general fatigue in attempting to compensate for the imprecise “stereo image”. Compensating for such misalignment should increase the time between when a surgeon commences a surgical procedure and when he or she becomes tired and thus less efficient at performing the procedure. Accordingly, it should enhance the overall comfort of the surgeon, enabling the surgical procedure to be performed in a more precise manner, by enhancing the optical comfort experienced by the surgeon during a surgical procedure.
It is an object of this invention to provide an imaging system which provides for adjustment of the working distance of a stereo endoscope. It is also an object of this invention to provide an imaging system which provides for alignment of the viewing axes of such a stereo endoscope. Further objects will be apparent from the following description of the preferred embodiments of the invention.